Improvement of D-Ribose Production from Corn Starch Hydrolysate by a Transketolase-Deficient Strain Bacillus subtilis UJS0717

Abstract

D-Ribose is a five-carbon sugar and generally used as an energy source to improve athletic performance and the ability. The culture conditions for maximum D-ribose production performance from cheap raw material corn starch hydrolysate were improved by using one-factor-at-a-time experiments and a three-level Box-Behnken factorial design. The optimal fermentation parameters were obtained as 36°C culture temperature, 10% inoculum volume, and 7.0 initial pH. The mathematical model was then developed to show the effect of each medium composition and their interactions on the production of D-ribose and estimated that the optimized D-ribose production performance with the concentration of 62.13 g/L, yield of 0.40 g/g, and volumetric productivity of 0.86 g/L·h could be obtained when the medium compositions were set as 157 g/L glucose, 21 g/L corn steep liquor, 3.2 g/L (NH4)2SO4, 1 g/L yeast extract, 0.05 g/L MnSO4·H2O, and 20 g/L CaCO3. These findings indicated the D-ribose production performance was significantly improved compared to that under original conditions.

Figure 1

Effect of temperature on D-ribose production performance of B. subtilis UJS0717 (fermentation time: 72 h; initial pH 7.0; inoculum volume: 10%, v/v; ^∗ P < 0.05 compared to 30°C group).

Figure 2

Effect of glucose concentration on D-ribose production performance of B. subtilis UJS0717 (corn steep liquor: 15 g/L; (NH₄)₂SO₄: 7.5 g/L).

Figure 3

(a) The 3D-plot and 2D-projection showing the interaction between glucose and corn steep liquor at 3.0 g/L (NH₄)₂SO₄ on D-ribose concentration (Y). (b) The 3D-plot and 2D-projection showing the interaction between glucose and (NH₄)₂SO₄ at 20 g/L corn steep liquor on D-ribose concentration (Y). (c) The 3D-plot and 2D-projection showing the interaction between corn steep liquor and (NH₄)₂SO₄ at 150 g/L glucose on D-ribose concentration (Y).

Figure 4

Comparison of D-ribose production performance of B. subtilis UJS0717 before and after optimization ((a) before optimization; (b) after optimization).